Preparation,Properties And Precision Machining Of Oversized Columnar Zirconia Ceramic

In this paper,three different ceramic forming methods were used to prepare ultra-large-sized zirconia columnar ceramics,and the sintered bodies were processed by three different precision machining processes which aim to further process the zirconia ceramic products.The effects of different molding methods on the microstructure,density and relative density of ultra-large-sized zirconia columnar ceramic green bodies,the effects of different molding methods on the microstructure,density and relative density of ultra-large-sized zirconia columnar ceramic sintered bodies and the influences of different precision machining processes on the processing performance of ceramic products prepared by different molding methods were studied.First of all,the large-size zirconia columnar ceramic molding process and the products prepared by them were studied.The results show that the particles of zirconia green body prepared by the rubber bag molding are small and compact,and their gaps are relatively smaller.The particles of the green body prepared by die forming method are larger and their gaps are large.The zirconia green particles prepared by plastic forming method are largest and the largest number of massive particles appear in the middle of a larger gap.The density of zirconia green body which prepared by rubber bag forming is 3.01 g/cm³and the relative density was 49.3%.The green density of the die molding is 2.96 g/cm³ and the relative density is 48.4%.The green body density of plastic molding is 2.93 g/cm³ and a relative density of 47.9%.The density of ultra-large zirconia columnar ceramic sintered body prepared by plastic molding is 5.998 g/cm³.The density of the ultra-large zirconia columnar ceramic sintered body prepared by die molding is 6.011 g/cm³.The density of the ultra-large zirconia columnar ceramic sintered body prepared by rubber bag molding is6.035 g/cm³.The flexural strength and fracture toughness of the zirconia columnar ceramic prepared by the rubber bag molding method are the highest,the flexural strength is 1078MPa,the fracture toughness is 8 MPa·m^1/2,the flexural strength and fracture toughness of the zirconia columnar ceramic prepared by plastic bag molding method and die molding are 7 MPa·m^1/2,but the zirconia columnar ceramic prepared by plastic bag molding has the lowest bending strength and its value is 878 MPa.The zirconia columnar ceramic prepared by die molding has the strongest hardness which is 13.2 GPa.The hardness of zirconia columnar ceramic made by rubber bag molding and plastic bag molding is basically the same and its value is about 12.8 GPa.The zirconia columnar ceramic prepared by rubber bag molding method has the highest thermal expansion coefficient and thermal conductivity,which are 11×10^-6K^-1 and 1.5 W·m^-1·k^-1,respectively.The thermal expansion coefficient of zirconia column ceramic prepared by plastic bag molding And the lowest thermal conductivity,the values were 9.5×10^-6K^-1 and 1.4 W·m^-1·k^-1.Secondly,the precision machining technology of ultra-large zirconia columnar ceramics was studied.The influences of different precision processing technologies on the processing performance of ceramic products prepared by different molding methods were analyzed and discussed.The results show that the three different precision machining processes are basically consistent after the ultra-large-size zirconia columnar ceramic proceeded by different molding methods.As the three molding methods are based on isostatic pressure,the product size are basically homogeneous because of the strong isostaic pressure.After the process of the precision machining,the process properties of products are basically the same indicators.Three kinds of columnar zirconia products prepared by different molding methods using high precision centerless grinding process have the lowest surface roughness,the steel mold is 0.02 um,the plastic bag molding is0.04 um,the rubber bag molding is 0.03 um.The surface roughness of the product was the highest which using the double roller co-grinding,the die molding is 0.04 um,the plastic bag molding is 0.05 um,the rubber bag forming is 0.03 um.The three kinds of columnar zirconia products prepared by different molding methods with high precision and unintentional grinding process have the highest friction resistance,the steel mold are 2.8million and 680 MPa respectively,the rubber bag are 2.6 million and 700 MPa respectively,the plastic bag molding are 2.5 million and 630 MPa respectively;the use of double roller co-grinding products with the lowest friction resistance and axial strength,the steel mold are 220 million and 630 MPa,respectively,the rubber bag molding are 200 million and650 MPa respectively,the plastic bag molding are 2.2 million and 615 MPa respectively.